ASTM D871-96(2010)
(Test Method)Standard Test Methods of Testing Cellulose Acetate
Standard Test Methods of Testing Cellulose Acetate
SIGNIFICANCE AND USE
Moisture content of the cellulose ester can be used to estimate the dry weight of the cellulose ester. Since cellulose esters are desiccants, their moisture content can vary greatly depending on storage.
SCOPE
1.1 These test methods cover procedures for testing cellulose acetate.
1.2 The test procedures appear in the following sections:
General Information
Relations
Standards Content (Sample)
NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation: D871 − 96 (Reapproved 2010)
Standard Test Methods of Testing
Cellulose Acetate
This standard is issued under the fixed designation D871; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
This standard has been approved for use by agencies of the U.S. Department of Defense.
1. Scope on Cellulose Esters by Potentiometric Titration—
Alternative Method
1.1 These test methods cover procedures for testing cellu-
lose acetate.
3. Purity of Reagents
1.2 The test procedures appear in the following sections:
3.1 Reagent grade chemicals shall be used in all tests.
Sections
Unless otherwise indicated, it is intended that all reagents shall
Ash 8 to 11
conform to the specifications of the Committee on Analytical
Color and Haze 67 to 72
Reagents of the American Chemical Society, where such
Combined Acetyl or Acetic Acid Content
Test Method A. Solution Method 17, 19 to 23
specifications are available. Other grades may be used, pro-
Test Method B. Heterogeneous Saponification Method 17, 24 to 26
vided it is first ascertained that the reagent is of sufficiently
Free Acidity 12 to 16
high purity to permit its use without lessening the accuracy of
Heat Stability 47 to 56
Hydroxyl Content 27 to 33
the determination.
Intrinsic Viscosity 57 to 62
Moisture Content 4 to 7
3.2 Unless otherwise indicated, references to water shall be
Primary Hydroxyl Content 34 to 39
understood to mean reagent tared, low, wide-form weighing
Sulfur or Sulfate Content 40 to 45
bottle and water, conforming to Specification D1193.
Viscosity 63 to 66
1.3 The values stated in SI units are to be regarded as the
MOISTURE CONTENT
standard. The values given in parentheses are for information
only. 4. Significance and Use
1.4 This standard does not purport to address all of the
4.1 Moisture content of the cellulose ester can be used to
safety concerns, if any, associated with its use. It is the
estimate the dry weight of the cellulose ester. Since cellulose
responsibility of the user of this standard to establish appro-
esters are desiccants, their moisture content can vary greatly
priate safety and health practices and determine the applica-
depending on storage.
bility of regulatory limitations prior to use.
5. Procedure
2. Referenced Documents
5.1 Transfer about5gofthe sample to a tared, low,
2.1 ASTM Standards: wide-form weighing bottle and weigh to the nearest 0.001 g.
D1193 Specification for Reagent Water Dry in an oven for2hat105 6 3°C. Remove the bottle from
D1343 Test Method for Viscosity of Cellulose Derivatives the oven, cover, cool in a desiccator, and weigh.
by Ball-Drop Method
6. Calculation
D2929 Test Method for Sulfur Content of Cellulosic Mate-
rials by X-Ray Fluorescence
6.1 Calculate the percentage of moisture as follows:
D5897 Test Method for Determination of Percent Hydroxyl
Moisture,% 5 A/B 3100
~ !
where:
These test methods are under the jurisdiction of ASTM Committee D01 on
A = weight loss on heating, g, and
Paint and Related Coatings, Materials, and Applications and are the direct
responsibility of Subcommittee D01.36 on Cellulose and Cellulose Derivatives.
CurrenteditionapprovedJune1,2010.PublishedJuly2010.Originallyapproved
in 1946. Last previous edition approved in 2004 as D871 – 96 (2004). DOI: Reagent Chemicals, American Chemical Society Specifications, American
10.1520/D0871-96R10. Chemical Society, Washington, DC. For suggestions on the testing of reagents not
For referenced ASTM standards, visit the ASTM website, www.astm.org, or listed by the American Chemical Society, see Analar Standards for Laboratory
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM Chemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeia
Standards volume information, refer to the standard’s Document Summary page on and National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville,
the ASTM website. MD.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D871 − 96 (2010)
13.2 Sodium Hydroxide, Standard Solution—(0.01 N)—
B = sample used, g.
Prepare and standardize a 0.01N solution of sodium hydroxide
(NaOH).
7. Precision and Bias
7.1 No statement on bias can be made as no reference
14. Procedure
material is available as a standard.
14.1 Shake5gofthe sample, ground to pass a No. 20 (850
ASH
µm) sieve and corrected for moisture content if necessary, in a
250-mL Erlenmeyer flask with 150 mL of freshly boiled, cold
8. Significance and Use
water. Stopper the flask and allow it to stand for 3 h. Filter off
8.1 Ash content gives an estimate of the inorganic content the cellulose acetate and wash it with water. Titrate the
of cellulose ester samples. The presence of high levels of
combined filtrate and washings with 0.01 N NaOH solution,
inorganic content (ash) can be detrimental to the melt stability
using phenolphthalein indicator solution.
and optical clarity of a cellulose ester in melt processing or act
14.2 Runablankdeterminationonthewater,usingthesame
as a potential source of insolubles when the ester is used in
volume as was used in extracting the sample.
solution.
15. Calculation
9. Procedure
15.1 Calculate the percentage of acidity as free acetic acid
9.1 Dry the sample for2hat105 6 3°C and weigh 10 to 50
as follows:
g, to the nearest 0.01 to 0.1 g, depending on its ash content and
Free acetic acid,% 5 @~A 2 B!N 30.06 3100#/W (1)
the accuracy desired. An air-dried sample may be used and
calculated to dry weight using the value for moisture deter-
where:
mined as in Sections 5 and 6. Burn directly over a flame in a
A = NaOH solution used to titrate the sample, mL,
100-mL tared platinum crucible that has been heated to
B = NaOH solution used to titrate the blank, mL,
constant weight and weighed to the nearest 0.1 mg. Add the
N = normality of the NaOH solution, and
sample in portions if more than 10 g is taken. The sample
W = sample used, g.
should burn gently and the portions should be added as the
flame subsides. Continue heating with a burner only as long as
16. Precision and Bias
the residue burns with a flame.Transfer the crucible to a muffle
16.1 No statement on bias can be made as no reference
furnace and heat at 550 to 600°C for 3 h, or longer if required,
material is available as a standard.
to burn all the carbon. Allow the crucible to cool and then
transfer it, while still warm, to a desiccator. When the crucible
COMBINED ACETYL OR ACETIC ACID CONTENT
has cooled to room temperature, weigh accurately to the
nearest 0.1 mg.
17. Scope
17.1 Two test methods are described for determining the
10. Calculation
combined acetyl or acetic acid content. The first, described in
10.1 Calculate the percentage of ash as follows:
Sections 19 to 22, is more precise, but less widely applicable,
Ash,% 5 A/B 3100
~ !
than the method described in Sections 24 to 26.
where:
18. Significance and Use
A = ash, g, and
18.1 Acetyl or acetic acid content is a measure of the
B = sample used, g.
amount of acetic acid esterified onto the cellulose backbone of
11. Precision and Bias
the polymer. The amount of substitution of acetate ester has a
very strong effect on the polymer’s solubility and physical
11.1 No statement on bias can be made as no reference
properties.
material is available as a standard.
Test Method A—Solution Method
FREE ACIDITY
19. Apparatus
12. Significance and Use
19.1 Weighing Bottle, glass-stoppered, 15-mL capacity,
12.1 Free Acidity is a measure of unesterified organic acid
25-mm diameter by 50-mm high.
in the ester. The presence of high levels of free acid is
potentially detrimental to the melt processing of the ester and
19.2 Tray, copper or aluminum, approximately 136.5 mm (5
can impact the odor of the ester. 3
⁄8 in.) square, containing 25 compartments 25.4 mm (1 in. )
square. Each compartment shall have the correct dimensions to
13. Reagents
contain one weighing bottle. The entire tray shall fit inside a
13.1 Phenolphthalein Indicator Solution (1 g/100 mL)— desiccator and should have a basket-type handle to facilitate
Dissolve1gof phenolphthalein in 100 mL of ethyl alcohol the introduction and removal of the tray (convenient but not
(95 %). essential).
D871 − 96 (2010)
19.3 Buret, automatic zero, 35-mL, 25-mL bulb, stem splashing the solution on the stopper. It is essential that
graduated from 25 to 35 mL in 0.05-ml increments; or pipet, complete solution be effected. Proceed in accordance with
automatic zero, 30-mL, for 1.0 N NaOH solution. 21.4.
19.4 Buret, automatic zero, 15-mL, 10-mL bulb, stem 21.3 If the acetyl content is 41 to 44.8 % or the acetic acid
graduated from 10 to 15 mL in 0.05-mL increments, for 1 N
content is 57 to 62.5 %, dissolve the sample by either of the
H SO . following two methods:
2 4
21.3.1 Gently rotate the flask by hand to distribute and
19.5 Buret, 5-ml, in 0.01 or 0.1-mL divisions, for back
spread the sample in a thin layer over the bottom of the flask.
titration with 0.1 N NaOH solution.
Add 70 mL of acetone to the flask and swirl gently until the
19.6 Magnetic Stirrer, for single flask.
sample particles are completely wetted and evenly dispersed.
19.7 Magnetic Stirrer, capacity twelve or more flasks. Stopper the flask and allow it to stand undisturbed for 10 min.
Carefully add 30 mL of dimethyl sulfoxide from a graduate to
19.8 Stirring Bars, stainless steel Type 416, length 50 mm,
the flask, pouring the solvent down the sides of the flask to
diameter 5 to 6 mm, or equivalent, dimensions not critical.
wash down any sample particles clinging to the side. Stopper
the flask and allow it to stand with occasional swirling until
20. Reagents
solution is complete. Magnetic stirring or gentle mechanical
20.1 Acetone—Add one 30-mL portion of 1.0 N NaOH
agitation that will not splash the solution is recommended.
solution to a mixture of 150 mLacetone and 100 mLhot water,
When solution appears to be complete, add 50 mL of acetone
allow to stand with frequent swirling for 30 min, and titrate
and swirl or stir for 5 min. Proceed in accordance with 21.4.
with 1.0 N H SO .Add another 30-mLportion of 1.0 N NaOH
2 4
21.3.2 Dimethyl sulfoxide is the preferred solvent, but if it
solution to 100 mLof hot water, allow to stand for 30 min, and
is not available, spread the sample in a thin layer over the
titrate. The difference between the two titrations shall not
bottom of the flask, add 15 mL of acetone, swirl to wet the
exceed 0.05 mL.
particles with acetone, stopper the flask, and allow the mixture
20.2 Dimethyl Sulfoxide.
to stand undisturbed for 20 min. Add 75 mL of pyridine
without shaking or swirling, and allow to stand for 10 min.
20.3 Pyridine.
Heat the solution just to boiling and swirl or stir for 5 min.
20.4 SodiumHydroxideSolution(40g/L)—Dissolve 40 g of
Again heat to boiling and swirl or stir for 10 min. Continue to
sodium hydroxide (NaOH) in water and dilute to 1 L.
heat and stir until the mixture is homogeneous and all large gel
20.5 Sodium Hydroxide, Standard Solution (0.1 N)—
masses are broken down into individual highly swollen par-
Prepare and standardize a 0.1 N solution of NaOH.
ticles. When these highly swollen gel particles are well
dispersed and are not fused together in large gel masses, no
20.6 SulfuricAcid (1.0N)—Prepare and standardize a 1.0N
further heating is necessary. Cool the flask, add 30 mL of
solution of sulfuric acid (H SO ).
2 4
acetone, and swirl or stir for 5 min. Proceed in accordance with
20.7 Phenolphthalein Indicator Solution (1 g/100 mL)—
21.4.
Dissolve1gof phenolphthalein in 100 ml of ethyl alcohol
21.4 Add 30 mL of NaOH solution (40 g/L) with constant
(95 %).
swirling or stirring to the solution of the sample and also to the
21. Procedure blank. Use of a magnetic stirrer is recommended (Note 2). It is
absolutely necessary that a finely divided precipitate of regen-
21.1 Dry 1.9 6 0.05 g of the ground well-mixed sample in
erated cellulose, free from lumps, be obtained. Stopper the
a weighing bottle for2hat105 6 3°C and weigh the dried
flask and let the mixture stand with occasional swirling, or stir
sample by difference to the nearest 1 mg into a 500-mL
on the magnetic stirring unit. Allow 30 min for saponification
wide-mouth Erlenmeyer flask. Prepare a blank by drying
of lower acetyl samples, 2 h for high acetyl samples when
approximately 3.8 g of potassium acid phthalate and weighing
dimethyl sulfoxide is the solvent, and 3 h when pyridine is the
it by difference into a flask as described. Carry the blank
solvent.At the end of the saponification period, add 100 mLof
through the entire procedure.
hot water, washing down the sides of the flask, and stir for 1 or
NOTE 1—Potassium acid phthalate is used so that the concentration of
2 min. Add 4 or 5 drops of phenolphthalein indicator solution
the NaOH in contact with the solvent in the blank will be approximately
and titrate the excess NaOH solution with 1.0 N H SO (Note
2 4
the same as that in contact with the sample and so that the titration of the
3). Titrate rapidly with constant swirling or stirring ring until
blank will be approximately the same as the titration of the sample, thus
the end point is reached; then add an excess of 0.2 or 0.3 mL
avoiding errors caused by using a different buret for the titration of the
blank and the sample or by refilling the 15-mLburet. If desired, however,
of H SO . Allow the mixture to stand with occasional stirring
2 4
the potassium acid phthalate may be omitted.
or preferably stir on the magnetic stirrer for at least 10 min.
21.2 If the acetyl content is 32 to 41 % or the acetic acid Then add 3 drops of phenolphthalein indicator solution to each
content is 45 to 57 %, put the sample into solution as follows: flask and titrate the small excess of acid with 0.1 N NaOH
Add 150 mL of acetone and 5 to 10 mL of water and swirl to solution to a persistent phenolphthalein end point. Take ex-
mix. Stopper the flask and allow it to stand with occasional treme care to locate this end point; after the sample is titrated
swirling until solution is complete. Solution may be hastened to a faint pink end point, swirl the mixture vigorously or place
bymagneticstirringorbyanysuitablemechanicalshakingthat it for a moment on the magnetic stirrer. If the end point fades
will provide a gentle rocking type of agitation to avoid because of acid soaking from the cellulose, continue the
D871 − 96 (2010)
addition of 0.1 N NaOH solution until a faint p
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